Latest Linux kernel has baked-in support for more cutting-edge ARM and MIPS processors, adds hardware support for Xen paravirtualuzation

The latest Linux kernel's revision number may be 3.14, but don't expect any pi jokes in the release notes. Do, however, look past the matter-of-fact release announcement on the Linux kernel development mailing list for some intriguing improvements in ways that may have implications for cutting-edge processors and for cloud/VM environments.

Most Linux releases either add or expand Linux's ability to run on a variety of processors, and 3.14 is no different, adding support for two key new processor types. First, and in some ways the most significant, is expanded support for various ARM system-on-chip solutions, such as HiSilicon and Freescale. ARM SoC solutions aren't just for smartphones anymore, but are fast becoming a part of future plans for high-density, low-power-consumption data center designs, with everyone from Red Hat to Microsoft (and, of course, the Open Compute Project) getting on board to be a part of it.

But another processor type with bolstered support in 3.14 are the MIPS interAptiv and proAptiv cores. MIPS processors -- now made by U.K. company Imagination Technologies after it bought MIPS Technologies in 2012 -- have been positioned as another way to create efficient data centers, although ARM has a jump on the market thanks to a broad base of users and developers. It's in Linux's best interests to support as broad a range of CPUs as possible, so merely having MIPS support in the kernel isn't by itself a ticket to architectural dominance. But it does mean a little less work needed on the part of Imagination, especially as it prepares its first 64-bit designs for later this year.

Other kernel additions in 3.14 have implications for the various cloud and VM architectures built around Linux. A major one is adding kernel support for Xen PVH -- using CPU-based paravirtualization (PV) extensions to accelerate the performance of the Xen hypervisor. Some of the details of Xen PVH aren't fully baked -- the ABI (application binary interface) hasn't been fully settled yet, for instance -- but the core is now in place.

Xen previously supported PV without relying on CPU extensions (Intel VT-x or AMD SVM), but Xen 4.4 added that hardware support for the sake of speed, and now such support is getting baked directly into the mainline kernel. (Xen, by the way, was ported to ARM in late 2011/early 2012, which added virtualization extensions in ARM v7-A.)

Xen's been one of the two big hypervisor technologies used in Linux, the other being KVM, which is now a major Red Hat project by way of Red Hat Enterprise Virtualization. Xen is under the governance of the Linux Foundation, and having hardware PV available in the kernel will by default be a major boon for those building their own Xen-powered cloud environments. It won't knock KVM out of the box -- let alone VMware's solutions or Microsoft Hyper-V -- but it provides one less reason to think poorly of the Xen architecture compared to its Linux hypervisor brethren.